Making Molds July 2001 Polyzine

POLYMER CLAY PUSH/FLEX MOLDS
BY TOIKA BRIDGES

Looking for the best way to make molds of your polymer clay originals or textures that you run across? Flex Mold material is great, and you can easily make your own molds!

Flex Mold uses RTV Silicone mold material. RTV means "room temperature vulcanizing," which just means that the mold cures at room temperature.

The benefits of making flex molds, besides their overall ease of use, are:

easy de-molding of the clay you have pushed into the mold -- even very complex, detailed molds -- with very little, if any distortion.
minimal use of mold releases. There is no need to attach a 'mushroom' of clay to the back of the pushed-in clay to pull it out of the mold, and then have to cut off the 'mushroom'.
this mold material captures and reproduces every tiny texture and detail.

Use only a '1 to 1' RTV Silicone mold material. This means one part of mold material A to one part of mold material B, or in other words, equal parts of both. Some RTV silicones are 4 to 1 or 6 to 1. They are very hard to measure correctly, which is one of the keys to success.

To show you how this mold material works, I am starting with a jewelry frame used for polymer clay jewelry and a real peacock feather.

STEP ONE:
Use a nonstick, clean surface as a base. I use Plexiglas.

I use spray adhesive on the back of the originals, and firmly press them onto the Plexiglas. (For more stability on the delicate peacock feather, I adhered the feather to a piece of thick cardboard with the spray adhesive, then affixed the cardboard to the Plexiglas.)

STEP TWO

Surround the objects with a mold frame made out of cardboard or mat board. Attach it with masking tape to the Plexiglas. This is to keep the mold frame in place and to keep the mold material from leaking out of the mold frame.

STEP THREE
Mix one part of mold material A with an equal part of the mold material B.

Stir about 40 seconds to a minute. You will then have about 15 minutes to work with the material before it starts to 'set-up'.

To avoid air bubbles, use a paintbrush to apply the liquid mold mix to the original. Then, just pour the mold mix into the mold frames.

Let the mold mix cure for the time specified by the manufacturer. I use one that cures in 4 hours.

STEP FOUR
Use a blunt table knife or craft knife to go around the edges, separating the cured mold from the cardboard mold frame, and pull/peel the mold out of the frame.

This was my first mold of a feather. I have never had to use mold release on any other object. But when I pulled the mold off the original feather, the mold mix had gotten so deeply into the details of the feather that some of the mold mix stayed with the feather and pulled off of the mold. Next time, I will use a mold release on a feather.

Just look at the detail.

STEP FIVE:
Push your clay into the mold, then put it in the freezer for about 5 minutes.

STEP SIX:
Using a polymer clay slicing blade, run along the top of the mold to take away the excess clay, then flex the mold to release your clay.

Before baking, I brushed on gold powder from LUCO(r) found mostly at art supply stores), and some Powdered Pearls(r) colors.

Molds are great for production work of the same piece, but they also allow for individualized work. You can press your own clay slices into a mold such as a cabochon shaped mold, then put in scrap clay behind it, and have your own original work produced at a faster rate.

You can be original each time, and put small clay components, slices of mokume gane, etc., into the mold, back it with scrap clay, and have a unique piece of your own work each time.

Molds are also great for making 'frames' for putting in your original work, and for making 'clay frames' for putting in Liquid Sculpey.

Never bake the silicone mold.

There are two types of RTV Silicone '1 to 1' molds that are especially good for polymer clay crafters: the liquid form demonstrated here and a putty type. The putty is great for when you are out and about and see a stone or other texture you want to have but can't take back home with you.

Mix equal parts of the putty mold mix A and mold mix B in your hand, then press it over the original, and it cures in 5 minutes! The putty is thick and dense and is, therefore, best used on non-delicate items, so you don't crush or distort the original. You can carry the cured putty mold around with you without fear of squishing or crushing it, however.

These same molds can be used to make castings with resins, plaster, and even pewter. (Pewter requires some more instruction and tools.) For more mold instruction, pre-made flex molds, small amounts of RTV Silicone liquid mold mix, and polymer clay project 'blanks' see my web page. When you are ready for larger quantities, a company called Micro Mark carries it.